Sara Gorman explores some of the factors behind anti-vaccination movements. Image credit: RIBI Image Library at Flickr Last year, polio eradication efforts were severely compromised by a rash of killings by militants in Pakistan and Nigeria. Between December 2012 and January 2013, at least 16 polio workers were killed in Pakistan. In early February, more bad news arrived: 9 health workers were murdered in northern Nigeria while working on the polio eradication campaign. Potential explanations and suggestions for future action poured out following the attacks.